Process for treating tar



March 17, 1953 J. w. DONEGAN 2,631,982

PROCESSFOR TREATING TAR Filed March 9, 1951 A 4 Sheets-Sheet 1 INVENTOR. JOSEPH w. DONEGAN AT TOR-N EY.

March 17, 1953 J. w. DONEGAN PROCESS FOR TREATING TAR 4 Sheets-Sheet. 2

Filed March 9, 1951 INVENTOR.

JOSEPH W. DONEGAN ATTORNEY.

March 17, 1953 J. w. DONEGAN PROCESS FOR TREATING TAR 4 Sheets-Sheet 5 Filed March 9, 1951 N M35523 M 2330 E v $52k? mm W E I I T N 3 N |v.||l| MEQZI W m :5: N m -3 w v A. um B b633 z 55:5

March 17, 1953 J. w. DONEGAN 2,631,982

PROCESS FOR TREATING TAR Filed March 9, 1951 4 heets-Sheet 4 JOSEPH 'w. DONEGAN BY ATTORNEY.

Patented Mar. 17, 1953 UNITED STATES PATENT OFFICE PROCESS FOR TREATING TAR Application March 9, 1951, Serial No. 214,774

Claims.

This invention relates to the treatment of tar and more particularly refers to a new and improved method of treating the tars obtained during the pyrolysis of coal or petroleum, exemplified by coke-oven tar, water-gas tar, oil-gas tar, or pitches of each, to produce therefrom a clarified tar eminently suitable as a saturant, and activated carbon.

A major use for tars and pitches is in the production of water and weather-resistant products by the impregnation of porous elements with molten pitch. Typical of such porous elements are roofing felt, fiber conduit, paper, etc. When normal coke-oven tar pitches or water-gas tar pitches or oil-gas tar pitches are used for the above purposes they often form objectionable deposits on the surface of the materials being impregnated and may so retard penetration as to make impregnation time excessive. In some cases this deposition and its effect on impregnation rate and product appearance are so objectionable as to make the use of the pitches employed commercially impracticable.

Microscopic examination of normal tars of the classes described discloses the presence of finely divided particles of opaque material suspended therein. Most of these particles are quite fine 2 micron) but some of the coarser material may exceed 10 micron size. It is considered that the shortcomings of the tar-pitches as saturants are attributable to blocking of the surface pores by these solid particles and the deposition of layers thereof on the surface as the fluid tar components filter through into the porous body. Various methods such as filtering, centrifuging, and the like, have been suggested for the separation of these solids from the tar, but, to the best of my knowledge, no commercial application has been made due to the difliculty of effecting such separation.

The suspended solid matter separated from the tar been considered a relatively useless byproduct unsuitable even as low value fuel without further treatment at additional expense.

Coal tar and coal-tar pitch derived therefrom are heavy hydrocarbons which may be termed a pyrogenous hydrocarbon condensate resulting from the destructive distillation of coals. Watergas tar and water-gas tar pitch derived therefrom and oil-gas tar and oil-gas tar pitch derived therefrom are heavy hydrocarbons which may be termed a pyrogenous hydrocarbon condensate resulting from the pyrolysis of petroleum at high temperature to produce predominantly gas.

An object of the present invention is to provide a method of converting tar containing naturally occurring finely divided particles of insoluble material suspended therein into a substantially optically clear tar eminently suitable as a saturant and activated carbons possessing great utility, e. g., for decolorizing, deodorizing, water purification and vapor adsorption.

Another object of the invention is to provide an efficient method of treating tars containing naturally occurring suspended solid particles to produce high yields of substantially optically clear tar having improved saturant properties.

A further object is to provide a method of sep arating the naturally occurring suspended solid material from tar containing the same and converting the separated solid material into superior activated carbons.

Other objects and advantages of the invention will be apparent from the description and accompanying drawings.

I have found that addition of about 0.15 to 0.75 volume of a selected solvent completely miscible with the fluid components of the tar to which it is added without causing secondary precipitation of normally tar-soluble components when admixed in these proportions, to 1.0 volume of tars containing naturally occurring finely divided solid matter, causes a flocculation of these suspended particles. in the absence of any substantial precipitation of fluid components from the tar, into coarse aggregations which are readily separated by filtering without blinding the filter cloth to yield a substantially optically clear filtrate containing little or no insoluble particles and having enhanced properties as a saturant, together with a filter cake suitable as raw material for conversion into high quality activated carbons.

A preferred method of carrying out this portion of my process involves mixing 0.2 to 0.5 volume of a predominantly aromatic solvent boiling within the range of F. to 450 F., e. g. benzene, toluene, xylene, and crude heavy solvent naphtha with crude tar thereby flocculating the suspended particles in the tar into coarse aggregations without effecting secondary precipitation of the fluid components from the tar, heating the mixture above about 200 F., preferably between 200 to 300 F., filtering the hot mixture to separate it into a tar substantially free from solid material and a filter cake of the solid material previously suspended in the crude tar, and distilling the tar filtrate to remove the solvent therefrom.

Further, the filter cake is washed with the solventto eliminate the bulk of adsorbed and occluded tar hydrocarbons, the washed material is then dried, preferably at a temperature below 230 F., to avoid fusion of the mass, the dried cake in the form of a finely pulverulent solid is compressed and granulated, and the granules are calcined in the presence of an oxygen-containing gas, preferably air, at gradually increasing temperatures from below 400 F. to not in excess of about 750 F. to avoid coalescence and fusion of the granules until an infusible activatable char is produced. The resultant char may be activated by conventional means, for example with steam or flue gases at high temperatures of the order of 17502200 F. to yield activated carbon products of highest quality as shown by standard criteria of activity. In my co-pending application Serial No. 18,712, filed April 2, 1948, now U. S. Patent 2,549,298, is described a method of calcining solid carbonaceous materials susceptible to activation.

Extensive examinations of coal tars, water-gas tars and oil-gas tars were made to determine their characteristics particularly with respect to the benzol-insoluble and quinoline-insoluble fractions of the tar and the physical appearance of the tars when magnified 300x by a microscope. The quinoline-insoluble fraction comprises those components which are insoluble in the fluid tar and which are visible therein when viewed under the microscope. The benzol-insoluble components include these solids and in addition include hydrocarbons which comprise a portion of the optically clear, fluid tar but are precipitated by the large volume of benzol employed in the test.

The benzol-insoluble contents referred to herein are determined by standard tests prescribed in Methods of Testing Coal-Tar Products (revised June 1950) published by The Barrett Division, Allied Chemical & Dye Corporation, 40 Rector Street, New York, copyright Allied Chemical & Dye Corporation 1931, 1942 and 1950.

In determining the-quinoline-insoluble content of a tar or pitch the sample (approximately 1 to 5 grams depending upon the insoluble content of the sample) is digested in 25 ml. of quinoline at 70-80 C. and filtered hot through a mat of diatomaceous earth. After washing with additional hot quinoline the crucible and contents are rinsed with benzene and then dried and weighed.

From my investigations I found that the quincline-insolubles constitute the filterable material which is so objectionable in saturating operations. Of greater significance, I discovered that the benzol-insoluble hydrocarbons beneficially affect the properties of the pitch saturant and, therefore, separation of the quinoline-insolubles is preferably accomplished without substantial removal of the quinoline-soluble benzol-insoluble components. Pitches which are deficient in these benzol-insoluble constituents tend to be brittle and of inferior mechanical strength. Another factor of great importance to successful commercial usage is the separation of the quinolineinsoluble from the tar at high filtration rates. The small size of the naturally occurring solid particles in the tar blind the filter cloth thus retarding the rate of filtration to an extent as to make it commercially unattractive. I have found that the difiiculties above mentioned may be obviated by the controlled addition of small portions of selected solvents which effect flocculation and facilitate separation at high filtration rates of the normally tar-insoluble tar components without precipitation of the normally tar soluble hydrocarbons.

A solvent suitable for use in the process of the present invention is one which is completely miscible with the fluid phase of the tar within the proportions (0.15 to 0.75 volume of solvent to 1.0 volume tar) required for flocculation of the insoluble dispersed phase and must cause no substantial secondary precipitation of the normally tar-soluble components within that rang 9 dilution. The optimum proportion of a solvent within the range of dilution may be easily determined by making incremental additions of that solvent to the tar and examining the mixture microscopically after each dilution to determine the state of dispersion of the insolubles.

In the course of extensive experimentation 1 investigated numerous solvents for use in my process. Solvents suitable for use in the practice of the present invention, 1. e. a solvent which is miscible with the tar and will flocculate the benzol-insoluble constituents without secondary precipitation when added in the proportion of 0.15-0.75 volume solvent to 1.0 volume tar, are aromatic, parafjnic and naphthenic hydrocarbons boiling substantially within the range of F. to 500 F; and carbon tetrachloride and acetone. Specific examples of these solvents are hexane, cyclohexane, benzene, toluene, xylene, decalin, naphthalene, crude heavy solvent naphtha, petroleum naphtha, kerosene, acetone and carbon tetrachloride. Such common solvents as creosote, carbon bisulfide, nitrobenzene, quincline, pyridine, phenol and cyclohexanone were found unsatisfactory due to failure to fiocculate the tar-insolubles or excessive dilution of the tar. Precipitation of the benzol-soluble components of tar may be easily discerned since the secondary precipitates of hydrocarbons are translucent brown flakes whereas the tar-insolubles are opaque and black.

In the practice of my invention I prefer to employ a predominantly aromatic solvent boiling within the range of F. to 450 F, more particularly a coal-tar, water-gas tar or oil-gas tar distillate boiling within such temperature range, benzene, toluene, xylene, and crude heavy solvent naphtha. Since these materials are normally found in the tar, they therefore can not contaminate any of the conventional distillate fractions and thus present an advantage over other useful solvents.

A petroleum distillate boiling substantially Within the range of 125 F. to 500 F., such as petroleum naphtha and kerosene may desirably be employed as the solvent because of its low cost.

In the photcmicrograph attached, Figure l (magnification 1200 the normal state of dispersion in a typical coke oven-tar is shown. The fine particles exhibit Brownian movement, and experiences have shown only the coarsest particles will settle out on lcng standing. The addition of a small amount of a selected solvent, for example 25% by volume of xylene, causes a fluocculation of these suspended particles into coarse aggregaticns which can be readily separated from the liquid phase by filtering. The photomicrograph, Figure 2, typifies the fluocculation induced by such addition to the tar of Figure 1. Filtration of this flocculated tar is easily effected and yields an optically clear filtrate which may be subsequently distilled to yield pitches containing virtually no insoluble particles.

Figure 3 is a diagrammatic flow sheet illustrating a preferred method of carrying out the present invention.

Referring to the drawing, crude tar and solvent are introduced through respective lines I and 2 in the proportion of about 0.15 to 0.75 part by volume solvent to one part by volume tar into mixing chamber 3. The contents of chamber 3 are agitated by stirrer d for a sufiicient length of time to assure thorough mixing, usually about 20 minutes is sufiicient, and during this time the mixture is heated to a temperature of about 200 F. to 300 F. by the introduction of steam through coil 5 immersed in the liquid. The mixture is then withdrawn from chamber 3 through line 6 and passed through filter I, wherein separation of the solid material from the liquid tar is eifected. The filtrate is then introduced via line 8 into shell still 9 mounted on furnace I! to effect distillation of the volatile constituents from the tar. Vapors evolved from still 9 are released through line 12, liquefied in condenser l3 and collected in vessels i l, l5 and i6. Distillate, consisting of the solvent added to the tar, flows through lines l1, l8 and valve is into tank M. This solvent may be returned via line 2| for further use in mixing chamber 3. A less volatile fraction, comprising carbolic oil, flows through line 11, valve 22, line 23 into tank P5. The following fraction, consisting of creosote oil, passes through lines ll, 24 and valve 25 into tank 16. If desired distillation may be continued to remove a heavier fraction from the shell still 9, and thereby produce residual pitch of high melting point. However, I have found it unnecessary in most instances to continue the distillation since the residual pitch remaining in shell still 9 after distillation of the creosote fraction is satisfactory as a pitch saturant and may be discharged from the still through line 26 into tank 21. Although coal tars which have been previously stripped of their carbolic and creosote oil components may be employed as a charging stock to the process, I prefer to use crude tar thereby eliminating a preliminary distillation and accomplishing separation of all the desired fractions from the crude tar by a single distillation operation.

The filter cake consisting of quinoline insolubles and adsorbed and occluded tar hydrocarbons from filter 1 is converted into activated carbon of high quality as follows: The filter cake is first washed with a solvent such as xylol or crude heavy solvent naphtha to eliminate the bulk of the tar hydrocarbons by transferrin the filter cake discharged from filter 1 via line 28 into tank 29 equipped with stirrer 3i and adding solvent through line 32 in the ratio of about 2-10 volumes of solvent per volume of filter cake. After the mixture of filter cake and solvent are stirred to dissolve the tar hydrocarbons in the solvent, the mixture is directed through line 33 to a conventional centrifuge 34 wherein separation of the insoluble components from the mixture is readily effected. Filtrate discharges from centrifuge 36 through line 35 and the moist filter cake is transferred through line 35 to drier 31 wherein the solids are heated to a temperature preferably not in excess of 230 F. and, if desired, at subatmospheric pressure. The dried solids, generally in the form of a finely pulverulent pow der, are passed through line 33 to conventional press 39 wherein powder is compressed at pressures ranging from 5000 to 50,000 p. s. i. into briquettes and thence through line H to conven tional crusher 42 wherein the briquettes are ground, and subsequently through line 43 to oscil lating screen 44 for sizing to the desired sized material, for example to through 4 on 50 mesh. The sized material from screen 44 is then conveyed through line 45 to calciner 46 which preferably is an externally heated rotary retort, equipped on one end with gas outlet 56 and on the opposite end with oxygen-containing gas inlet 57. Since the granular material is susceptible to fusion the granular solids are heated at gradually increasing temperatures from below 400 F., preferably from below 300 F. to within the range of 400-750" F. in the presence of oxygencontaining gas. During the charring operation a stream of air at the rate within the range of about 1.5-7.5 cubic feet per pounds of material per minute is passed through the retort. Calcination is continued until there is obtained an infusible char without permitting fusion of the granules or leaving incompletel reacted fusible residues.

The calcined granules are then transferred through line 58 into activator 59 which may be a rotary retort. Charred granules are activated by passing steam or flue gases through line 6| in contact with the granules at a temperature in the general order of 1750 to 2200 F. and discharging the spent gases from the retort through line 62. The activated carbon is discharged from activator 59 through line 63. 4

For the purpose of more clearly illustrating the advantage of increased filtration rate by the use of the present invention tests were conducted wherein crude coke-oven tar, crude coke-oven tar diluted with creosote oil, crude coke-oven tar diluted with xylol, and crude coke-oven tar diluted with petroleum naphtha were filtered under comparable conditions. In conducting these tests, the stock tank was charged with the charging material and brought to temperature. The heated material was then pumped to a preheated filter chamber consisting of a vessel adapted to be maintained under pressure and enclosing a cloth filter septum. These tests were run at a temperature of 300 F. C.) and a pressure of 35 p. s. i. gauge. The material which filtered prior to attaining full pressure (minor in amount) was rejected, although a record was kept of the amount of this forerun. Time readings were taken at various weighed increments of filtrate.

and the filtration rate and yield were calculated from these data. The results of these tests are summarized in the following examples.

crude coke-oven tar (100 volumes) creosote oil (37 volumes) Material filtered Temperature 150 C. Pressure 35 p. s. i. Forerun yield 3.05 lbs/sq. ft.

Filtrate Yield Time, Minutes Filtration Rate, lbs/sq. lbs/sq. ft. Midpoint Total At ft/hr o o 0 o o 4. so 2. 4s 4. 0a 4. 0a 72. 2 9. 72 7. 29 11.50 7. 47 38.9 14. 5s 12. 15 21.05 9. 55 so. 5 19. 44 17.01 32.15 11.10 26.1 24. 30 21.87 45. 4o 13. 25 22. 0 29. 1e 26. 73 so. 87 15. 47 18.8 34. 02 51. 59 78.30 17. 43 16. 7

Example 3 crude. coke-oven tar- Material filtered 100 volumes) Xylol (25 volumes). Temperature 150 C. Pressure 35 p. s. i. Forerun yield 4.7 lb./sq. ft.

Ifilti'ate Yield Time, Minutes Filtration Rate, lbs/sq. lbs/sq. r1. Midpoint Total At Example 4 crude coke-oven tar Material filtered (100 volumes) xylol (46 volumes) Temperature 150 C. Pressure 35 p. s. i. Forerun yield 3.7 lbs/sq. ft.

Filtrate Yield 1 Time, Minutes Filtration Rae, lbs/sq. I 15 111. lbs/sq. ft Midpoint Total At 0 Q 0 0 o 4.35 2. 43 1.17 1.17 249. 0 9. 72 7. 29 2. 97 1 1.30 151. 0 14. 53 12. 15 5. 15 g 2.19 133. 0 19. 44 17. 01 7. 73 1 2.57 113. 0 24. 30 21. 37 10.57 i 2. 34 102.0 29. 15 25. 73 13.70 i 3. 13 93. o 34. 02 31. 59 17.13 3. 43 33. 3 33. 33 35. 20. 33 3. 55 79. 7 43. 74 41. 31 24.32 i 3. 99 73. 0 43. 45. 17 29. 05 4. 24 53. 9 53. 45 51. 03 33.50 I 4. 44 55. 5 53. 32 55. 39 33. 13 4. 53 52. 3 53. 13 50. 75 42. 33 1 4. 70 52. o 53. 04 55. 51 47. 33 1 4. 35 50. 1 72. 90 70. 47 53. 50 I 5. 57 51. 4

Example 5 crude coke-oven tar Material filtered (100 volumes) sun spirits 1 (25 volumes) Temperature 150 C. Pressure 35 p. s. 1. Forerun yield 2.0 lb./q. ft.

Commercial petroleum naphtha having a flash point above 100 F. and an end point not over 400 F.

Filtrate Yield Time, Minutes Filtration Rate, lbs/sq. lbs/sq 11 Midpoint Total At 0 0 o o 0 4. 35 2. 43 2. 43 2. 43 119. 0 9. 72 7. 29 5. 77 3. 34 37. 1 14. 53 12.15 9. 55 3. 73 77.1 19. 44 17. 01 13. 77 4. 22 59. 0 24.39 21.37 13. 57 4. 9o 59. 4 29.15 25. 73 23. 30 5.13 55. 7 34. 02 31. 59 29. 75 5. 95 43. 9 33. 33 35. 45 35. 2o 5. 45 45. 1 43. 74 41. 31 43. 33 7. 13 4o. 7

The data from the above examples show the effectiveness of the flocculant addition in increasing filtration rate. That the great increase in filtration rate and sustained rate at high throughput is not due simply to dilution efiects by the xylol is demonstrated by the data which clearly show that even 37 parts of creosote is inferior to 25 parts of xylol as a fiocculant and aid to filtration. Addition of 46 parts of xylol shows still further increase in filtration rate indicative of stronger flocculation of the dispersoid.

Referring again to the above data it is obvious that straight tar cannot be filtered at any practicable rate and the plugging of the pores of the filter quickly reduces this rate. Similarly, when creosote oil is used as the diluent, filtration rate and the permissible yield are both low. Addition of xylene or petroleum naphtha in the proportion of 25% by volume of the tar results in a markedly increased filtration rate as well as the sustained rate of high throughput. Thus, the foregoing improvements in the clarification of tar are made possible by the addition to. the tar of small portions of a selected solvent which, While miscible with the fluid components of the tar, causes flocculation of the dispersoid. Creosote oil and similar high boiling distillates do not cause flocculation of the insoluble material and, as a consequence, simply dilute the tar Without afiecting the state of the dispersion of such solid particulate matter.

In Figure 4 the filtration rate in pounds of filtrate per square foot of filter area per hour is plotted against cumulative yield in pounds of filtrate per square foot of filter area when filtering coke-oven tar Without the addition of any diluent, coke-oven tar plus 37 parts of creosote oil, coke-oven tar plus 25 and 46 parts of xylol, and coke-oven tar plus 25 parts of petroleum naphtha. From Figure 4 the marked advantage of employing the flocculating agent in the desired proportion'in the present invention will be readily apparent.

The following examples illustrate the present invention for the treatment of tar for the production of pitch saturant and activated carbon.

Example 6 One volume of coke-oven tar containing 6.1% quinoline insolubles was mixed with 0.35 volume of xylene, the mixture then heated to a temperature of 300 F., and the heated mixture passed through a cloth filter maintained under pressure of 40 p. s. i. gauge. The filtrate was distilled directly to pitch of 152 F. softening point (ring and ball). The filtrate tar Was optically clear and the pitch product analyzed less than 1% quinoline insolubles.

The filter cake obtained by filtering the crude coke-oven tar was admixed with 3 volumes of Xylene and the mixture agitated for about 30 minutes. The mixture was then centrifuged and the resultant filter cake dried at a temperature of 200 F. The dried residue analyzed 90.4% benzol-insoluble and 86.6% quinoline insoluble. This finely powdered material was briquetted at 5000 p. s. i. to give a briquette having a density of 0.90 gram/00., and then the briquettes granulated to a 10, +20 mesh grain. The granulated material was then calcined in a rotary retort by passing air therethrough at the rate of 5 cubic feet per pounds of material per minute while gradually heating the granulated material in the retort from 300 F. to 725 F. over a period of about 4 hours. No fusion. sintering or bloating of the grain occurred. Activation of a portion of this calcined grain using steam at 1790 F. gave a product of such activity that aesipsa 9 0.25 grain removed 87% of the iodine from a Standard iodine solution.

Activation of another portion of the calcined grain at 2010" F. with steam yielded a decolorizing carbon of such activity that when pulverized to pass a No. 200 sieve, 0.5 gram removed 89% of the color from a standard sugar solution. A commercial carbon evaluated in comparison removed 75% in the same test.

Example 7 One volume of an oil-gas tar analyzing 18% quinoline-insoluble was diluted with 0.5 volume of xylol and filtered at 212 F. and 15 p. s. 1. gauge. The filter cake was washed with an additional 1.5 volumes of xylol and dried. After briquetting at 300 p. s. i. the briquettes were crushed to 10-20 mesh grain and calcined and activated as in Example 6. The activated product had an iodine value of 88%.

Although certain preferred embodiments of the invention have been disclosed for purpose of illustration, it will be evident that various changes and modifications may be made therein without departing from the scope and spirit of the invention.

I claim:

1. A process for the treatment of heavy hydrocarbons containing naturally occurring finely divided particles suspended therein selected from the group consisting of coal tar, water-gas tar, oil-gas tar and their pitches which comprises admixing a solvent selected from the group consisting of aromatic, naphthenic, and paraffinic hydrocarbons boiling substantially within the range of 125 F. to 500 F., carbon tetrachloride, and acetone in the proportion of 0.15-0.75 volume solvent to 1.0 volume heavy hydrocarbon, thereby fiocculating the suspended particles in the heavy hydrocarbon into coarse aggregations without erfecting substantial secondary precipitation of fluid components from the heavy hydrocarbon, and separating the mixture into a heavy hydrocarbon substantially free from solid material and a cake of the solid material previously suspended in the heavy hydrocarbon.

2. A process for the treatment of heavy hydrocarbons containing naturally occurring finely divided particles suspended therein selected from the group consisting of coal tar, water-gas tar, oil-gas tar and their pitches which comprises admixing a predominantly aromatic solvent boiling within the range of 170 F. to 450 F. with the heavy hydrocarbon in the proportion of 0.20.5 volume solvent to 1.0 volume heavy hydrocarbon, thereby fiocculating the suspended particles in the heavy hydrocarbon into coarse aggregations without effecting substantial secondary precipitation of fluid components from the heavy hydrocarbon, and separating the mixture into a heavy hydrocarbon substantially free from solid material and a cake of the solid material previously suspended in the heavy hydrocarbon.

3. A process for the treatment of heavy hydrocarbons containing naturally occurring finely divided particles suspended therein selected from the group consisting of coal tar, water-gas tar, oil-gas tar and their pitches which comprises admixing a petroleum distillate boiling substantially within the range of 125 F. to 500 F. with the heavy hydrocarbon in the proportion of 0.2- 0.5 volume solvent to 1.0 volume heavy hydrocarbon, thereby flocculating the suspended particles in the heavy hydrocarbon into coarse a gregations without efiecting substantial sec- 10 ondary precipitation of fluid components from the heavy hydrocarbon, and separating the mixture into a heavy hydrocarbon substantially free from solid material and a cake of the solid material previously suspended. in the heavy hydrocarbon.

4. A process for the treatment of heavy hydrocarbons containing naturally occurring finely divided particles suspended therein selected from the group consisting of coal tar, water-gas tar, oil-gas tar and their pitches which comprises admixing carbon tetrachloride with the heavy hydrocarbon in the proportion of 0.15-0.75 volume solvent to 1.0 volume heavy hydrocarbon, thereby fiocculating the suspended particles in the heavy hydrocarbon into coarse aggregations without effecting substantial secondary precipitation of fluid components from the heavy hydrocarbon, and separating the mixture into a heavy hydrocarbon substantially free from solid material and a cake of the solid material previously suspended in the heavy hydrocarbon.

5. A process for the treatment of heavy hydrocarbons containing naturally occurring finely divided particles suspended therein selected from the group consisting of coal tar, water-gas tar, oil-gas tar, and their pitches which comprises admixing a solvent selected from the group consisting of aromatic, naphthenic and paraffinic hydrocarbons boiling substantially within the range of F. to 500 F., carbon tetrachloride and acetone with the heavy hydrocarbon in the proportion of 0.15-0.75 volume solvent to 1.0 volume heavy hydrocarbon, thereby flocculating the suspended particles in the heavy hydrocarbon into coarse aggregations without efiecting substantial secondary precipitation of fluid components from the heavy hydrocarbon, heating the mixture above 200 F., filtering the hot mixture to separate it into a. heavy hydrocarbon substantially free from solid material and a filter cake of the solid material previously suspended in the heavy hydrocarbon, and subjecting the filtrate to distillation to remove the solvent therefrom.

6. A process for the treatment of heavy hydrocarbons containing naturally occurring finely divided particles suspended therein selected from the group consisting of coal tar, water-gas tar, oil-gas tar and their pitches which comprises admixing a predominantly aromatic solvent boiling within the range of F. to 450 F. with the heavy hydrocarbon in the proportion of 0.2- 0.5 volume solvent to 1.0 volume heavy hydrocarbon, thereby fiocculating the suspended particles in the heavy hydrocarbon into coarse aggregations without effecting substantial secondary precipitation of fluid components from the heavy hydrocarbons, separating the mixture into a heavy hydrocarbon substantially free from solid material and a cake of the solid material previously suspended in the heavy hydrocarbon, washing the cake of solid material with a solvent to effect removal of adsorbed and occluded heavy hydrocarbon from the cake or solid material, heating the solids materials in the presence of oxygencontaining gas at temperatures sufiiciently high to char the solids while maintaining the temperature sufliciently low during such heating so that at least a substantial proportion of the solid remains in an unfused condition, and continuing heating of the solid until an iniusible activatable char is obtained.

7. A process for the treatment of coal tar con-- tai i naturally occurring finely divided particles suspended therein which comprises admixing a predominantly aromatic solvent boiling within the range of 170 F. to 450 F. with the coal tar in the proportion of 0.2-0.5 volume solvent to 1.0 volume coal tar thereby fiocculating the suspended particles in the tar into coarse aggregations without effecting substantial secondary precipitation of the fiuid components from the tar, heating the mixture above 200 F. filtering the hot mixture to separate it into a tar substantially 'free from solid material and a filter cake of the solid material previously suspended in the tar, distilling the tar filtrate to remove the solvent therefrom, washing the filter cake with a solvent to eliminate the bulk of adsorbed and occluded tar hydrocarbons, drying the washed solid at a temperature sufliciently low to avoid fusion of the mass, compressing the dried solids, granulating the compressed solids, and heating the granules in the presence of air at gradually increasing temperatures from below 400 F. to not in excess of about 750 F. to avoid coalescence and fusion of the granules until an infusible activatable char is produced.

'8. A process for the treatment of crude coal tar containing naturally occurring finely divided "particles suspended therein which comprises admixing 'an aromatic hydrocarbon boiling within the range of 170 F. to 300 F. with the tar in the proportion of 02-05 volume of aromatic hydrocarbon 'to 1L0 volume tar, thereby fiocculating the suspended particles in the tar into coarse a gregations without effecting secondary precipitation of the fluid components from the tar, filtering the hot mixture to separate it into a tar substantially free of solid material and a filter cake of the solid materialpr'e'viously suspended in the tar, -distilling the tar-filtrate to remove the aroinatic hydrocarbon, c'arb'olic oil, and creosote oil therefrom, washing thefilter cake with a solvent to eliminate the bulk of adsorbed and occluded tar hydrocarbons, drying the washed filter cake at 'a'teniperature of below'230" 'F. to avoid fusion of the mass, compressing'the dried filter cake into briquettes at pressures within the range of 5000 to 50,000 p. s. i., grinding and granulating the briquettes to about through e on 50 mesh, heating 'the granular solids in the presence of air at gradually increasingtemperatures to "avoid fusion of the mass or the granular solids from below "300 FIto'Within the range of 400-750" F. until an infusible char is obtained, and activating the 'granular infusible char to produce activated carbon.

9. A process for the treatment of crude coal tar containing naturally occurring finelydivided particles suspended therein which comprises admixing xylene with the tar in the proportion of 0.2-0.5 volume Xylene to 1.0 volume tar, thereby flocculating the suspended particles in the tar into coarse aggregations without efiecting secondary precipitation of the fiuid components from the tar, filtering the hot mixture to separate it into a tar substantially free of solid material and a filter cake of the solid material previously suspended in the tar, distilling the tar filtrate to remove xylene, carbolic oil, and creosote oil therefrom, washing the filter cake with a solvent to eliminate the bulk of adsorbed and occluded tar hydrocarbons, drying the washed filter cake at a temperature of below 230 F. to avoid fusion of the mass, compressing the dried filter cake into briquettes at pressures within the range of 5000 to 50,000 p. s. i., grinding and granulating the briquettes to about through 4 on 50 mesh, heating the granular solids in the presence of air at gradually increasing temperatures to avoid'fusion of the mass of the granular solids from below 300 F. to within the range of 400750 F. until n infusible char is obtained, and activating the granular infusible char to produce activated carbon.

10. A process for the treatment of heavy hydrocarbon containing naturally occurring finely divided particles suspended therein selectedfrom the group consisting of coal tar, water-gas tar, oil-gas tar and their pitches which com-prises admixing a solvent selected from the group consisting of aromatic, naphthenic and parafilnic hydrocarbons boiling substantially within the range of F. to 500 F., carbon tetrachloride and acetone inthe proportion of 0.15-0.75 volume solvent to 1.0 volume heavy hydrocarbon required to effect flocculation-of the suspended particles 'in the heavy hydrocarbon into coarse aggregations without efiecting substantial secondary precipitation of the fluid componentsfrom the heavy hydrocarbon, and separating the mixture into a heavy hydrocarbon substantially freefrom solid material and a cake of the solid materialpreviously suspended in theheavy hydrocarbon.

J-OSEPHW. DONEGAN.

REFERENCES "CI-TED The following'referencesare-of record in the file of this patent:

V UNITED STATES PATENTS Number Name Date 1,355,099 Weiss Oct. 5,1920 1,796,815 Ullrich Mar. 17, 1931 2,549,298 Donegan Apr. 17,1951 

1. A PROCESS FOR THE TREATMENT OF HEAVY HYDROCARBONS CONTAINING NATURALLY OCCURRING FINELY DIVIDED PARTICLES SUSPENDED THERIN SELECTED FROM THE GROUP CONSISTING OF COAL TAR, WATER-GAS TAR, OIL-GAS TAR AND THEIR PITCHES WHICH COMPRISES ADMIXING A SOLVENT SELECTED FROM THE GROUP CONSISTING OF AROMATIC, NAPHTHENIC, AND PARAFFINIC HYDROCARBONS BOILING SUBSTANTIALLY WITHIN THE RANGE OF 125* F. TO 500* F., CARBON TETRACHLORIDE, AND ACETONE IN THE PROPORTION OF 0.15-0.75 VOL- 